function s1_generate_a_series_of_files(){
    for i in {1..100};do 
    echo $i>/tmp/new_file$i;done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
    ls -l /etc/{passwd,shadow,group,gshadow} |sort -d
}
function s3_find_items_related_to_given_username(){
   grep -h $1 /etc/{passwd,shadow} |sort -d
}
function s4_find_items_related_to_given_group_name(){
    grep  -h  $1/etc/{group,gshadow} |sort -d
}
function s5_create_groups_for_given_group_names(){
    groupadd rnd && groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
    useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin &&  useradd -G itoperation david && useradd -G rnd edward
}
function s7_change_users_shell(){
     usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
   passwd -n 10 -x 60 -w 10 adam
   passwd -n 10 -x 60 -w 10 bob
   passwd -n 10 -x 60 -w 10 david
   passwd -n 10 -x 60 -w 10 calvin
   passwd -n 10 -x 60 -w 10 edward
}
function s9_set_password_for_five_users(){
   usernames=(adam bob calvin david edward)
   passwords=($1 $2 $3 $4 $5)
   for i in {0..4};do
   echo "${usernames[i]}:${passwords[i]}" | chpasswd
   done
}
function s10_lock_bobs_password(){
   usermod  -L bob
}
function s11_include_adam_into_wheel_group(){
    usermod -aG wheel adam
}
function s12_change_files_permission(){
 for i in {1..33};do 
 chmod 640/tmp/new_file$((3*i))
 expected="-rw-r-----"
 actual=$(ls -l/tem/new/new_file$((3*i)) |awk'{print $1}')
 [["$actual"=="$expected"]] || echo"failed"
 done
}

